The present invention relates generally to the fields of cancer and chemotherapy and more particularly, to the field of diagnostic and prognostic methods for the same. The invention provides a method that analyzes the relative amount of GADD153, as a function of the magnitude of the increase in GADD153 expression following DNA damage, as a clinical tool in monitoring and detectng tumor damage in response to a chemotherapeutic agent or other anti-cancer treatment.
The accurate quantitation of the extent of tumor injury in patients as a result of treatment is often a problem. Normally, the effectiveness of chemotherapy or radiation therapy cannot be determined for at least several weeks and often longer. This presents an obstacle to improving the management of cancer patients particularly when alternative therapeutic modalities are available. Quantitation of molecular events occurring in response to injury in the tumor in vivo following cytotoxic injury may permit more rapid assessment of the likelihood of response (20,21).
Cells cope with injury by changing their pattern of gene expression, and some of these same changes occur in common in different types of cells. Transcription of the proto-oncogenes, c-fos and c-jun, for example, is rapidly induced by exposure to a wide variety of exogenous stimuli including, cytotoxic agents (1,2,3). The expression of these xe2x80x9cearly response genesxe2x80x9d results in the rapid induction of many other genes, primarily regulated at the level of transcription (4,5). Holbrook et al. reported the isolation of a DNA damage-inducible gene, GADD153, from hamster (6) and human cells (7). GADD153 was one of 5 different genes found to be coordinately induced by either growth arrest or agents that cause DNA damage (8). They demonstrated that the GADD153 promotor was responsive to a broad spectrum of genotoxic agents, and subsequent work has provided evidence that the activation of the GADD153 promotor occurred as a direct result of DNA damage.
Elucidation of the molecular processes involved in the cellular injury response is yielding opportunities for the identification of novel markers that reflect the extent of injury produced in tumors by treatment with chemotherapeutic agents (23). Work in laboratories has identified GADD153 as an important player in the cellular injury response.
GADD153 is a gene that is strongly transcriptionally activated by cDDP (11,24) as well as by other types of cellular stress (25), including other classes of chemotherapeutic drugs (10,26). Among the genes whose message levels are known to increase following cellular injury, GADD153 is of particular interest as a potential marker because of the magnitude of its induction.
The GADD153 gene is unique in that it is not responsive to TPA despite the presence of an AP-1 binding site, distinguishing itself from other response genes such as the xe2x80x9cearly responsexe2x80x9d gene, C-JUN, and heat shock family genes. However, GADD153 can undergo inducible phosphorylation on two adjacent serine residues by a specific stress activated MAP kinase (29) which enhances the ability of GADD153 to function as a transcriptional activator (29). Prior observations of the present inventors showed that GADD153 is functionally located downstream of a hypothetical injury detection site as shown by the induction kinetics of GADD153, but upstream of the cell cycle control and cell growth events (23,29). GADD153 may serve as a link between early and late events in the response to cellular damage. However, its specific use as a marker for the extent of the cellular injury response has not been proposed nor tested.
In comparison to many other genotoxic agents and treatments, cDDP causes an unusually rapid activation of the GADD153 promotor (10). The mechanism responsible for the activation of GADD153 expression following DNA damage is still unclear.
Although other diagnostic and prognostic methods for tumor response to clinical therapy exist, none have found broad application due to their inherent limitations. The need remains for an improved prognostic and/or diagnostic method for tumor clinical response to chemotherapy.
Data by the present inventors demonstrate that GADD153 is induced by DNA damage in a dose dependent manner. In one aspect, the present invention provides a method for predicting a patient""s therapeutic response to chemotherapy. In one embodiment, the method provides a GADD153 mRNA-based prognostic method for assessing clinical response by a tumor to chemotherapeutic agent. The present method is advantageously much more rapid than known prognostic methods, and requires only minimal invasion of a patient. The present method accurately predicts tumor clinical response to chemotherapeutic agents and can be used to predict tumor progression or partial as well as complete regression after treatment with a chemotherapeutic agent, through assessment of the magnitude of increase in GADD153 mRNA present in a sample derived from the tumor.
Accordingly, in some embodiments, the present invention provides a prognostic method for clinical response by a tumor to a chemotherapeutic agent comprising: administering a chemotherapeutic agent to a patient having a tumor; and determining the magnitude of increase above a control baseline for GADD153 mRNA in a sample derived from said tumor a period of time after administration of said chemotherapeutic agent; said magnitude of increase above baseline in GADD153 mRNA being predictive of a clinical response by said tumor.
In yet another aspect, the invention provides a prognostic method wherein a tumor biopsy is used to assess relative GADD153 mRNA levels in a subject having been treated with a chemotherapeutic agent.
In some embodiments, determination of the magnitude of increase, above baseline, in GADD153 mRNA is done during one or more of various time periods following administration of a chemotherapeutic agent. It is contemplated that the best time periods after administration of the chemotherapeutic agent for determination of the magnitude of increase above baseline, in GADD153 mRNA can vary according to the tumor being treated and the chemotherapeutic agent being used. Specifically, the determination of the magnitude of increase, above baseline, in GADD153 mRNA in a sample derived from a tumor can be done about 6 to about 72 hours after administration of a chemotherapeutic agent.
The magnitude of increase in GADD153 mRNA in a sample derived from a tumor treated with a chemotherapeutic agent will be determined relative to the expected or observed magnitude of increase, i.e. the baseline, in a sample derived from the same tumor but not treated with the chemotherapeutic agent. Generally regarding the therapeutic benefit received by a tumor-bearing patient undergoing chemotherapy, the larger the observed magnitude of increase in GADD153 mRNA, the greater the therapeutic benefit received by the patient.
In some embodiments, where the tumor is a head or neck carcinoma, and the chemotherapeutic agent being used includes cisplatin, the magnitude of increase, above baseline, in GADD153 mRNA in the range of less than about 7-fold indicates a tumor clinical response of tumor progression. In another embodiment, the magnitude of increase, above baseline, in GADD153 mRNA is in the range of greater than or equal to about 1 to less than or equal to about 2-fold, the tumor clinical response indicated is partial regression. In yet another embodiment, where the magnitude of increase, above baseline, in GADD153 mRNA is in the range of greater than about 2-fold, the tumor clinical response indicated is regression. It is contemplated that the limits for magnitude of increase, above baseline, in GADD153 mRNA can overlap while still providing an accurate prognostic method.
It is contemplated that the present methods can be applied in vivo, ex vivo and/or in vitro with a wide range of tumors in mammals. A broad range of chemotherapeutic agents and tumor types are contemplated by the invention as well.
In another embodiment, the present invention provides that changes in GADD153 mRNA may be quantitatively linked to the extent of tumor cell kill in vitro. In yet another embodiment, changes in GADD153 mRNA are quantitatively limited to the dose of chemotherapeutic agent, using cells grown as xenografts in vivo. In a further embodiment, the invention provides that the magnitude of increase in GADD153 mRNA level be measured after administration of cisplatin and that the level indicated is correlatable to the tumor clinical response in a patient with advanced head and/or neck carcinoma.
Yet another embodiment of the invention provides a method whereby the magnitude of increase in GADD153 mRNA measured after administration of paclitaxel or progesterone in combination with paclitaxal is correlatable to the tumor clinical response in the tumor-bearing patient.
Another aspect of the invention provides a screening method for the detection of tumor clinical response to chemotherapy. Thus, the invention also provides a GADD153 mRNA-based diagnostic method for tumors. This aspect of the invention is particularly advantageous over known diagnostic methods, as it provides rapid and accurate diagnostic information for a broad range of tumors. Accordingly, this aspect of the invention provides a GADD153 mRNA-based prognostic method for tumor clinical response to a chemotherapeutic agent comprising administering a chemotherapeutic agent to a patient having a tumor; and determining the magnitude of increase above baseline in GADD153 mRNA in a sample derived from said tumor a period of time after administration of said chemotherapeutic agent; said magnitude of increase above baseline in GADD153 mRNA being predictive of a clinical response by said tumor.
In some embodiments, the magnitude of increase above baseline, in GADD153 mRNA in a sample derived from the tumor is done about 12 to about 48 hours after administration of the chemotherapeutic agent, or in some uses, between about 12 to about 48, or about 24 hours, after administration of the chemotherapeutic agent. Based on the magnitude of difference in GADD153 mRNA observed, the clinical response indicated by use of the particular chemotherapeutic agent is tumor progression, partial tumor regression or complete tumor regression.